Interactions between organic compounds and olivine under aqueous conditions: A potential role for organic distribution in carbonaceous chondrites

Olivine is a principal anhydrous silicate mineral in chondritic meteorites. The structure of this mineral is composed of independent SiO₄ tetrahedra linked by divalent cations (mainly Mg). Under hydrothermal conditions, olivine is transformed into serpentine, which is a major hydrated phyllosilicate in the matrix of carbonaceous chondrites. Although carbonaceous chondrites contain various types of organic matter, the interaction between organic compounds and olivine at low temperature has not been considered in the literature. We performed an experiment to test the adsorption of N-containing organic compounds (i.e., alkylpyridines and alkylimidazoles) on olivine using liquid chromatography under aqueous conditions (pH = 2.5–10.5) at 20–40 °C. The N-containing cyclic compounds were interacted with the SiO₄ tetrahedra of olivine and their different adsorption abilities depended on the organic structures. Because alkylpyridines often occur at different locations than alkylimidazoles in carbonaceous chondrites, the results of this study suggest that olivine can separate the N-containing compounds associated with aqueous fluid flows by asteroidal chromatography in the meteorite parent body. Liquid chromatography based on solid phase minerals may hence be a useful technique for simulating the behavior of organic compounds in carbonaceous asteroids under aqueous activity.